It looks very clean indeed. Here is an example of docs for the getElementById method.

You will see that it has basic info, compatibility charts (although they are minimal… saying things like “buggy” instead of why), and hints.

For example:

The behavior of this method when more than one element of the specified ID exists is not standardized, because a document is not allowed to contain more than one element with the same ID. But for reference, in this situation all browsers return the first element found.